As gun rail mounting systems progressed from the Weaver type to the Picatinny type there were other variants that were custom to a particular manufacturer such as Glock. This resulted in the unsatisfactory situation where Picatinny rail accessories were not backwards compatible with Weaver mounts and neither of those were compatible with manufacturers custom mounts such as Glock.
Accessory companies either offered unique mounting hardware for the different rail types or in some cases offered different plastic inserts that would fit the different widths of recoil locking slots.
This invention has specific application in the mounting of a video camera where the ability to have the camera mounted on the gun rail facing in either direction and also allowing the mounting hardware to be flipped forwards to backwards and up or down gives the user four times as many position options as the typical rail mounting hardware.